Embodiments of the present embodiments relate to an audio system with filters programmed in response to an integral hearing test.
Normal human hearing is generally considered to range from 20 Hz to 20 kHz. It is typically displayed on a logarithmic scale in units of decibels SPL (Sound Power Level) or simply dB. For example, 0 dB corresponds to a power of 10−16 watts/cm2. This is about the weakest sound detectable by the human ear. Normal speech may be around 60 dB, and hearing damage may occur around 140 dB.
Human hearing is most sensitive to sounds between 1 kHz and 4 kHz. But speech comprehension also depends on higher frequency components found in consonants. For example, consonants such as f, j, s, v, and z are often important to speech comprehension but comprise frequencies from 3 kHz to 8 kHz. With increasing age, many people lose the ability to hear these higher frequency components and experience diminished speech comprehension. Hearing aids, telephone amplifiers, and other devices may improve comprehension. Some of these devices, however, only amplify the entire bandwidth from 20 Hz to 20 kHz. Thus, midrange frequencies from 1 kHz and 4 kHz may still overpower higher frequencies that assist in speech comprehension. Some programmable hearing aids are designed to selectively amplify frequency bands corresponding to individual hearing loss and, thereby, improve hearing and speech comprehension. However, these hearing aids typically require an audiogram from a trained audiologist. Furthermore, they must be reprogrammed as hearing is further diminished. The inevitable result is a significant time and cost overhead for users.
Finally, many hearing aids will not work with simple devices such as telephone handsets or portable electronic devices with earphones. Simply increasing the volume of a telephone amplifier often produces feedback resulting in a loud squeal. Furthermore, many hearing aids are less effective in groups where several people may be talking. Thus, there is a significant need for improved, affordable hearing devices that will enhance speech comprehension without the need of a trained audiologist.